Cadillac P1635: 5-Volt Reference 1 Circuit Malfunction

What Does The Cadillac P1635 Code Mean?

Engine started; and the PCM detected an out-of-range voltage condition on the 5v Reference 1 circuit for 1 second. The PCM uses the 5v VREF 1 circuit connects to the MAP sensor, EGR Valve Pintle position sensor and Throttle Position sensor.

What Are The Potential Causes Of The Cadillac P1635 Code?

• 5v VREF circuit is shorted to sensor ground or chassis ground
• 5v VREF circuit or MAP sensor circuit is shorted to power (B+)
• 5v VREF circuit shorted to EGR sensor High signal circuit
• EGR solenoid valve (and sensor) is damaged or has failed
• PCM has failed

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> ACDelco GM Original Equipment 12690512 Vapor Canister Purge Valve
>>> GM Genuine Parts 12633238 Engine Control Module

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

GM, 2013, Service Bullettin – Prior To Any Circuit Testing.